If you want to use the Google Maps API you must obtain a key from the Google site to be able to use it, but to apply for key must have a certificate, which is called MD5. The following step-by-step explanation:
Step 1:
If you are using eclipse to write an Android program, then open Eclipse->windows→preference→android→build, where default debug The value of KeyStore is the path of Debug.keystore, copied down.
Step 2:
Execute command: Keytool-list-keystore debug.keystore, you may be prompted to enter the password, here Enter the default password "Android", you can get the MD5 value.
Step 3:
Open Web page: Https://developers.google.com/maps/documentation/android/start#installing_the_google_maps_android_v2_api, (Login to Google account first, there is no sign up on the line, this is not a big problem.) Click Creating an API Project, then click on Google APIs Console. Then click on the servises in the left-hand column to scroll down in the list on the right, knowing that you found the Google Maps API v2 and then clicked on the switch, To make its state open.
Step 4.
Click on the left Sidebar API Access, on the right side of the page to click Create New Android key, this will pop up a page, in the input box, enter the certificate you obtained before, the format is Xxxxxxxxx;com.example, Here Com.example is your Android project with the package name, and then click Create to generate the corresponding API key, copy key, and then in your Android project Androidmanifest.xml add key on the line, as for the specific implementation next time.
"Go" request Google API Key